The HiDPI Scaling Issue
If you install Ubuntu Linux on a modern laptop with a 4K display, or connect a high-resolution external monitor, the GNOME desktop environment will detect the high pixel density (HiDPI) and automatically apply a 200% display scale. While this prevents your icons and text from being microscopically small, a strict 200% scale often makes everything look comically large, wasting the massive screen real estate you paid for. If you manually change it back to 100%, everything is too small. When you reboot or disconnect the monitor, Ubuntu often automatically forces the 200% scale right back on.
How to Enable Fractional Scaling
To stop Ubuntu from bouncing between the extremes of 100% and 200%, you need to unlock the hidden “Fractional Scaling” feature, which allows you to set precise, permanent middle-ground resolutions like 125% or 150%.
1. Open the main Ubuntu Settings application.
2. In the left-hand sidebar, scroll down and click on Displays.
3. Look for the toggle switch labelled Fractional Scaling.
4. Turn this switch On.
5. A warning may appear stating that fractional scaling increases power usage or lowers sharpness on some legacy apps. Accept the warning.
6. You will now see new options in the “Scale” list (e.g., 125%, 150%, 175%).
7. Select your preferred scale and click Apply.
Enabling Fractional Scaling via Terminal (Wayland)
If the toggle switch is missing from your Settings menu (a common issue depending on your graphics drivers or if you are using the Wayland display server), you must forcefully enable the feature via the terminal.
1. Open your terminal.
2. Run the following command exactly: gsettings set org.gnome.mutter experimental-features "['scale-monitor-framebuffer']"
3. Reboot your computer. When you return to the Displays settings menu, the 125% and 150% options will be permanently unlocked and available for use.